JP3837762B2 - Ion exchange resin separation and regeneration method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for separating and regenerating an ion exchange resin forming a mixed bed, in particular, separation of a mixed bed ion exchange device used in a condensate demineralizer, separation and regeneration of an ion exchange resin suitable for regeneration. Regarding the method.
[0002]
[Prior art]
In a power plant, it is necessary to maintain the water quality of the feed water at a higher level from the viewpoint of corrosion of system materials due to impurities in condensate and prevention of turbine scale. For this reason, as a condensate demineralizer for recirculating and using condensate as feed water, a mixed bed type ion exchange desalination apparatus capable of obtaining high treated water quality is used.
[0003]
The treated water quality of the mixed bed type ion exchange desalting apparatus is determined by the regeneration state of the ion exchange resin, but in order to make the regeneration state of the resin higher, it is necessary to prevent reverse regeneration as much as possible. Reverse regeneration means that when an anion exchange resin is mixed with an acid solution such as hydrochloric acid or sulfuric acid, the anion exchange resin is regenerated into a Cl form or SO ₄ form, and the anion exchange is mixed with a cation exchange resin. When the resin is regenerated with an alkali solution such as sodium hydroxide, the cation exchange resin is regenerated to Na form or the like.
[0004]
Therefore, in order to prevent reverse regeneration, when regenerating the ion exchange resin forming the mixed bed, the cation exchange resin and the anion exchange resin are separated as close as possible to each other, It is necessary to reduce the mixing of the anion exchange resin and the mixing of the cation exchange resin into the anion exchange resin as much as possible.
[0005]
The condensate demineralizer (mixed-bed ion exchange demineralizer) is separated from the desalting tower and completely separated from the regeneration tower so that acid or alkali, which is the regenerant of the ion exchange resin, does not enter the condensate. When regeneration is necessary, the desalting tower is separated from the main system, and the resin in the desalting tower is separated by pressurized water and pressurized air and transferred to the regeneration tower for regeneration.
[0006]
Separation of the ion exchange resin forming the mixed bed is performed by developing the resin layer with upward circulating water called backwashing, and separating the cation exchange resin and the anion exchange resin by the difference in specific gravity and the difference in particle diameter. This is not limited to the condensate demineralizer, and the same applies to a general mixed-bed ion exchanger used for other purposes.
[0007]
As is well known, new ion exchange resins have a strong charge on their surfaces. For this reason, when a new cation resin and an anion resin are regenerated and mixed in the RH and R—OH forms, the ion exchange resin agglomerates due to a strong attractive force. The aggregation of the resin in this manner is preferable for desalting because the cationic resin and the anionic resin are uniformly and well mixed.
[0008]
However, at the time of regeneration of the desalting apparatus, the aggregation hinders separation of both resins, which is not preferable. In particular, since the new desalination apparatus uses a new ion exchange resin, the resins strongly aggregate due to the strong surface charge. In addition, in the initial stage of the use, the regeneration is performed before the exchange capacity is completely used, so that the RH and R—OH type exchange groups remain, and strong aggregation occurs.
[0009]
Even if backwashing is performed in a state where such agglomeration occurs, it is difficult to completely separate both resins. The strength of this agglomeration varies depending on the ion form of the ion exchange resin, the type of resin (gel type, porous type), etc., but completely destroys the agglomeration and completely separates the resin by backwashing. Preventing the occurrence is necessary to keep the water quality of the desalinizer good.
[0010]
When the resin to be regenerated is in an agglomerated state, neutralizing the surface charge is effective for destroying the agglomeration of the resin. Therefore, the resin into which an appropriate amount of the clad in the condensate has flowed is attached to the resin surface, and the aggregation state is relaxed.
However, in the latest power plants, the amount of clad generated has been reduced due to water quality management and material improvements, and it cannot be expected that the clad resin will break down due to the clad.
[0011]
In order to destroy the aggregation of the resin, there is a method in which the charge of the resin itself is neutralized by an ion load. Usually, hydrochloric acid or sodium hydroxide is used to break up the aggregated state and separate the resin. However, the added ions are adsorbed on the ion exchange resin, and these ions have a large adsorbing power. Therefore, a very large amount of regenerant is required to desorb them.
[0012]
For example, if hydrochloric acid is used, the anion exchange resin is converted into a chloride ion form, and regenerating it into an R-OH form for use in desalting requires a large amount of a regenerant and is uneconomical. Moreover, if sodium hydroxide is added, the cation exchange resin becomes R-Na type, and this sodium easily leaks from the resin, which is likely to cause deterioration of water quality. In order to keep the boiler water quality good, the Na ion form must be removed. For this reason, it is necessary to use a large amount of regenerant and completely regenerate it.
[0013]
[Problems to be solved by the invention]
The object of the present invention is to solve the above-mentioned problems, and can break up the aggregation of the resin by a simple operation using an inexpensive material, thereby improving the separation accuracy between the anion exchange resin and the cation exchange resin. At the same time, it is to propose a method for separating and regenerating an ion exchange resin that can increase the regeneration efficiency, reduce the amount of the regenerant used, and obtain good treated water quality.
[0014]
[Means for Solving the Problems]
The present invention is a method for separating and regenerating the following ion exchange resin.
(1) In a method for separating and regenerating an ion exchange resin forming a mixed bed,
Contacting the ion exchange resin in a mixed state with a carbon dioxide-containing gas containing 10% by volume or more of carbon dioxide ;
Separated into a cation exchange resin layer and an anion exchange resin layer by backwashing,
A method for separating and regenerating an ion exchange resin, wherein each resin layer is regenerated by contacting with a regenerant.
(2) The supply amount of the carbon dioxide-containing gas is 3 to 50 volume times the resin amount of the ion exchange resin in the mixed state, and the supply flow rate is 0.3 to ⁵ m ³ −gas / m ³ −resin / min. The method according to (1) above, wherein
(3) The above (1) or (1), wherein the separation and regeneration of the ion exchange resin forming the mixed bed is the first to tenth separation and regeneration after the addition of a new resin or after the replenishment of the resin. 2) The method described.
[0015]
The method of the present invention can be applied to separation and regeneration of any ion exchange resin as long as it is a regeneration of an ion exchange resin in which an anion exchange resin and a cation exchange resin are mixed to form a mixed bed. It can also be applied to a mixed bed type ion exchanger of the final stage of a two-bed / three-column mixed bed type, and is particularly preferably applied to separation and regeneration of an ion exchange resin used in a condensate demineralizer.
[0016]
The condensate demineralizer often regenerates outside the tower, and other mixed bed ion exchangers often regenerate inside the ion exchange tower, but the method of the present invention can be applied to any of these methods. In addition, in order to improve the separation property, a method in which a resin having an intermediate specific gravity is mixed, or an intermediate resin near the separation interface is excluded from the regeneration process and regenerated at the next regeneration, or after regeneration without regenerating the intermediate resin. In some cases, a method of mixing with the above resin and transferring to the desalting step may be employed, but the method of the present invention can also be applied to these cases.
[0017]
In the present invention, the resin agglomeration state of the mixed bed type ion exchange apparatus using the cation exchange resin and the anion exchange resin as described above is improved, the separation property of the resin is improved, and a good regeneration state with little reverse regeneration is realized. can do. In particular, it is effective for the first to tenth resin separation and regeneration after the addition of a new resin or after the replenishment of the resin, but it can also be applied to subsequent separation and regeneration.
[0018]
In the present invention, in the backwash separation after the desalting using the mixed bed type ion exchange resin, the mixed ion exchange resin is brought into contact with the carbon dioxide-containing gas, but prior to the backwash separation or during the backwash. It is preferable to blow in a carbon dioxide-containing gas. The carbon dioxide-containing gas used here may be a mixture of carbon dioxide and air, an inert gas, or other gas in addition to pure carbon dioxide gas. Such carbon dioxide concentration of carbon dioxide-containing gas is 10 volume% or higher, preferably 50 volume% or more.
[0019]
For backwashing separation of resin during regeneration of mixed bed type ion exchange resin, air is introduced prior to water backwashing or with water backwashing in addition to water backwashing in which only water flows upward. In some cases, air backwashing that disturbs the resin layer is performed. In the present invention, instead of such air backwashing, a carbon dioxide-containing gas can be introduced and brought into contact with the ion exchange resin.
[0020]
The carbon dioxide injected here is easily dissolved in water, and the dissolved carbon dioxide exists as bicarbonate ions. Since a large amount of anion exchange resin having a large amount of ion exchange capability exists in the regeneration tower, a part of these bicarbonate ions is exchanged and adsorbed to form HCO ₃ . These equations are shown below.
[Chemical 1]
CO ₂ + H ₂ O → H ⁺ + HCO ₃ ⁻ [I]
H ⁺ + HCO ₃ ⁻ + R—OH → R—HCO ₃ + H ₂ O [II]
[0021]
Carbon dioxide remaining in the water dissociates as shown in the above formula [I], and ions are slightly increased, thereby lowering the pH of the water present in the tower. The change in pH greatly affects the aggregating action, and the agglomeration of the resin is destroyed. The bicarbonate ions adsorbed on the anion exchange resin are considered to have an action of neutralizing the surface charge of the anion resin, and the aggregation of the resin is similarly destroyed. Furthermore, the regenerated water in which carbon dioxide is dissolved has a low pH and has an effect of efficiently peeling off the clad adsorbed on the ion exchange resin.
[0022]
Therefore, when carbon dioxide-containing gas is supplied from the bottom of the resin layer prior to the backwash separation of the mixed resin layer or with water backwash, the carbon dioxide destroys the aggregation of the resin due to the above-described action, and the upward flow of bubbles The resin is disturbed to separate the resin particles, and the iron clad and other dirt attached to the resin are also peeled off. The supply of the carbon dioxide-containing gas at this time is optional, but it is preferably 3 to 50 times the volume of the resin, and the flow rate is 0.3 to ⁵ m ³ -gas / m ³ -resin / min. Is preferred.
[0023]
After cohesive failure and removal of dirt by supplying the carbon dioxide-containing gas described above, if the supply of carbon dioxide-containing gas is stopped and only water backwashing is performed, the ion exchange resin to be regenerated is separated due to the difference in specific gravity. The cation exchange resin having a high specific gravity is laminated on the bottom, and the anion exchange resin having a low specific gravity on the top.
[0024]
When both resins are regenerated in separate towers, the anion exchange resin is transferred to the anion regeneration tower in the above state, and the cation exchange resin is allowed to settle as it is. When both resins are regenerated in the same tower, the water backwashing is finished in the same state, and the resin is allowed to settle.
[0025]
In this way, even when cohesive failure is caused by carbon dioxide-containing gas, in order to achieve a more complete separation of both resins at the resin interface, an inert resin with an intermediate specific gravity is used as described above, or the resin near the interface is recovered from the regeneration process. It can also be excluded.
[0026]
If you do not choose this type of operation, select the former with less harmful effects by weighing the harmful effects of mixing the anion exchange resin into the cation exchange resin and the harmful effects of mixing the cation exchange resin into the anion exchange resin. In the regeneration tower, some anion exchange resin is left on the upper part of the cation exchange resin layer, and the anion exchange resin hardly mixed with the cation exchange resin can be transferred to the anion regeneration tower for regeneration.
[0027]
The regeneration is the same as the regeneration of a general ion exchange resin, and each resin layer is brought into contact with a regenerant. The contact method is preferably a method in which a regenerant solution is passed through each ion exchange resin layer.
[0028]
In the case of a cation exchange resin, the regenerant is an acid aqueous solution such as 2 to 10% by weight sulfuric acid or hydrochloric acid. In the case of an anion exchange resin, an alkaline aqueous solution such as 2 to 10% by weight sodium hydroxide or potassium hydroxide is used. Use. In the case of a condensate demineralizer, it is preferable to use sulfuric acid and sodium hydroxide and perform regeneration outside the tower in separate towers. In the case of other general mixed bed type ion exchangers, hydrochloric acid and sodium hydroxide are often used.
Conditions such as the flow rate of the regenerant, extrusion, and water washing are the same as in the case of normal regeneration.
[0029]
In the present invention, the anion exchange resin is in the HCO ₃ form by contact with the carbon dioxide-containing gas, and the HCO ₃ form resin is easily regenerated by sodium hydroxide. Here, “easy to be regenerated” means that the bicarbonate ion adsorbed on the anion exchange resin is easily desorbed by sodium hydroxide and is easy to regenerate, and also from sodium chloride directly with sodium hydroxide. This means that the regeneration efficiency is better than that in the case of regeneration, and regeneration with a small amount of regenerant is possible.
[0030]
If the total resin becomes Cl, SO ₄ , Na, etc. using hydrochloric acid, sulfuric acid, or sodium hydroxide for cohesive failure, a large amount of regenerant must be added to make this form OH or H. Although it is necessary, in the present invention, it is easy to convert the HCO ₃ form to the OH form and the regeneration efficiency is good, so that it can be efficiently regenerated with a small amount of regenerant.
[0031]
【The invention's effect】
According to the present invention, the ion exchange resin in a mixed state is brought into contact with a carbon dioxide-containing gas containing 10% by volume or more of carbon dioxide, and the resin is separated and regenerated by backwashing with water. The material can be used to break the resin agglomeration by a simple operation, thereby improving the separation accuracy between the anion exchange resin and the cation exchange resin, increasing the regeneration efficiency, and reducing the amount of regenerant used. Thus, it is possible to obtain a method for separating and regenerating an ion exchange resin capable of obtaining good treated water quality.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the invention will be described focusing on an example in which an ion exchange resin of a mixed bed ion exchange apparatus in a condensate demineralizer is regenerated outside the tower.
[0033]
FIG. 1 is a system diagram showing an ion exchange resin regeneration process in a mixed bed ion exchange apparatus of a condensate demineralizer. In FIG. 1, 1 is a desalting tower, 2 is an ion exchange resin packed in the desalting tower 1, 3 is a cation regeneration tower (also used for resin separation), 3a, 3b and 3c are strainers for collecting water, 3d is strainer for dosing, 3e collector, 4 anion regeneration tower, 4a, the 4b strainer for collection and distribution of water, the intermediate resin storage tank 5, V ₁ ~V ₂₂ is valve.
[0034]
In the above configuration, the regeneration of the ion exchange resin 2 in the condensate demineralizer is usually performed as follows. First, the valves V ₁ , V ₂ , V ₈ , V ₁₃ , V ₁₄ , V ₁₅ are opened (the other valves are closed, the same applies hereinafter), and air is supplied from the flow path 6 and water is supplied from the flow path 7. By introducing into the desalting tower 1, the ion exchange resin 2 forming the mixed bed is transferred to the cation regeneration tower 3 through the flow path 8. At this time, the water introduced into the cation regeneration tower 3 is discharged from the flow paths 9 and 10 at the top of the cation regeneration tower 3.
[0035]
After transfer completion of the introduction of water and air is stopped, by opening the valve V ₅ and drain pauses by lowering the liquid surface 11.
Thereafter, the valves V ₈ and V ₁₂ are opened, a gas containing carbon dioxide is blown from the flow path 12 through the strainer 3c, the resin layer is loosened, and the deposits are peeled off and the aggregation of the resin is destroyed.
[0036]
After stopping the blowing of carbon dioxide-containing gas, the valves V ₁ , V ₈ , V ₁₁ are opened, water is introduced from the flow path 12, the water is backwashed in an upward flow, the resin layer is developed, and the separated sewage And the cation exchange resin and the anion exchange resin are separated.
[0037]
Opening and separating the resin layer and opening the valves V ₁₇ and V ₁₉ with the lower part of the anion exchange resin layer (the upper part of the intermediate resin layer mixed with the resin near the interface) aligned with the collector 3e, the anion exchange resin is It is transferred from the channel 13 to the anion regeneration tower 4.
When the valve V ₁₆ is opened with the valves V ₁₇ and V ₁₉ closed and the lower part of the intermediate resin layer (the upper part of the cation exchange resin layer) aligned with the collector 3e, the mixed resin in the intermediate resin layer is transferred from the flow path 14 to the intermediate resin storage tank. 5 is transferred.
[0038]
The resin layers of the cation regeneration tower 3 and the anion regeneration tower 4 are stopped, the valves V ₃ , V ₆ , V ₁₈ , V ₁₉ are opened, and a regenerant (acid aqueous solution or alkali aqueous solution) is injected from the channels 15, 16, respectively. Then, a chemical injection is carried out, and further, the same amount of water is injected and extrusion is performed. Then, the valves V ₇ and V ₁₀ are opened and washed with water to regenerate the cation and anion exchange resin.
[0039]
After completion of the regeneration, the valves V ₄ , V ₉ , V ₂₀ and V ₂₁ are opened, and the regenerated resin is transferred from the flow paths 17 and 18 to a resin storage tank (not shown) and stored in a mixed state. The stored resin is taken out for the next regeneration and transferred to the emptied desalting tower 1 to be desalted.
[0040]
On the other hand, the intermediate resin stored in the intermediate resin storage tank 5 is transferred to the cation regeneration tower 3 by opening the valves V ₁ , V ₂ and V ₂₂ , and separated and regenerated at the next regeneration. When the intermediate resin storage tank 5 is omitted, the drawn intermediate resin is transferred to the resin storage tank and can be transferred to the desalting tower 1 together with the regenerated resin at the next desalting without being regenerated.
[0041]
The above is a preferred embodiment showing a method for regenerating the ion exchange resin in the condensate demineralizer, but in the case of regeneration of the mixed bed type ion exchanger in a general pure water production apparatus or the like, without regeneration outside the tower. The cation and anion exchange resin may be separated and regenerated in the desalting tower 1 in some cases.
In this case, carbon dioxide-containing gas is blown from the strainer 1a to unravel the resin, and after removing the dirt and cohesive failure, backwashing with water is performed to separate the cation and anion exchange resin layer.
[0042]
And while draining from the strainer 1b provided in the vicinity of the resin interface, water flows upward from the tower bottom to the cation exchange resin layer, and a regenerant (alkaline aqueous solution) is poured from the strainer 1c to pour the anion exchange resin layer. Regeneration is performed, and extrusion is performed by injecting substantially the same amount of water. Thereafter, water flows downward from the upper part of the tower to the anion exchange resin layer, and a regenerant (acid aqueous solution) is poured from the strainer 1a to regenerate the cation exchange resin. Further, almost the same amount of water is injected. Extrude.
[0043]
After washing both resin layers with water, air is blown from the bottom of the tower to stir the resin layer, and a mixed bed is formed by mixing the cation and anion exchange resin, and the regeneration process is completed. Thereafter, the water flow is resumed and the ion exchange process is started.
[0044]
The regeneration for separating and regenerating the resin in one tower as described above may be performed in a regeneration tower provided separately from the desalting tower. In this case, after transferring the resin from the desalting tower to the regeneration tower, the above operation is performed, and after regeneration, both resins are returned to the desalting tower and mixed.
[0045]
In some cases, the desalting tower is used as a cation regeneration tower, and the anion exchange resin is regenerated in another regeneration tower. In this case, after blowing the carbon dioxide-containing gas and backwashing separation in the desalting tower, the anion exchange resin is transferred to the regeneration tower, and each resin is regenerated. After regeneration, the anion exchange resin is returned to the desalting tower and mixed.
[0046]
In addition, there are various separation and regeneration methods depending on the purpose, but in any case, when backwashing the mixed resin, carbon dioxide-containing gas is blown to cause cohesive failure and improve the separation of both resins. .
[0047]
【Example】
Examples of the present invention will be described below. In each example,% is% by weight.
[0048]
Comparative Example 1
The test was conducted with an apparatus having the following specifications simulating the condensate desalination apparatus of FIG. The desalting tower 1 is a columnar tower having a tower diameter of 350 mmφ and a height of 2.1 m. The cation regeneration tower 3 is a columnar tower having a tower diameter of 250 mmφ and a height of 3.1 m. The anion regeneration tower 4 is a columnar tower having a tower diameter of 150 mmφ and a height of 3.1 m.
[0049]
This demineralization tower is filled with 85 liters of freshly regenerated cation exchange resin and 40 liters of freshly regenerated anion exchange resin, mixed and mixed with a synthetic condensate containing 1 mg / l NH ₃ at a flow rate of 10 m ³ / h. Then, the resin was transferred to the cation regeneration tower 3. Then, the resin layer was loosened by air backwashing, and after removing the dirt, both resins were separated by water backwashing, and the upper anion exchange resin was transferred to the anion regeneration tower 4. Subsequently, the upper resin 6 liter of the resin remaining in the cation regeneration tower was transferred to the intermediate resin tank as an intermediate resin.
[0050]
As a result of the first regeneration of the resin with sulfuric acid as the cation exchange resin and sodium hydroxide as the anion exchange resin, the ratio of the R-Na form to the total cation exchange groups of the regenerated cation exchange resin was 1.2%. The ratio of the R—Cl form to the total anion exchange groups of the later anion exchange resin was 18%.
[0051]
The regenerated resin was washed with water, transferred to the desalting tower 1 and mixed, and the synthetic condensate was passed through in the same manner as in the previous cycle. The resin after passing water was transferred to the regeneration tower in the same manner as described above, and the second regeneration operation was performed in the same manner.
The ratio of the R—Na form to the whole cation exchange group after regeneration was 0.6%, and the ratio of the R—Cl form to the whole anion exchange group after regeneration was 15%.
[0052]
Similarly, as a result of the third regeneration, the R-Na form ratio is 0.4%, the R-Cl form ratio is 13%, and the fourth regeneration result is that the R-Na form ratio is 0. .15%, R-Cl form ratio was 10%.
In the reproduction after 10 times of such repetition, the R—Na type ratio was 0.15% and the R—Cl type ratio was 6%, which was almost the same value as the ninth reproduction result.
[0053]
Example 1
In the same apparatus as Comparative Example 1, the resin was replaced with a new resin, and the same operation was performed. However, after the resin was transferred from the desalting tower to the regeneration tower, a carbon dioxide- containing gas containing 100% by volume of carbon dioxide was injected at 150 N liter / min for 7 minutes instead of the air backwashing in Comparative Example 1, and then water was added. A backwash separation operation was performed. Other operations are the same as those in Comparative Example 1.
[0054]
As a result of the first regeneration, the ratio of the R—Na form to the entire cation exchange group after regeneration was 0.4%, and the ratio of the R—Cl form to the entire anion exchange group after regeneration was 8%.
The ratio of the R—Na form after the second regeneration was 0.3%, and the ratio of the R—Cl form was 6.5%.
[0055]
The third regeneration result is the ratio of R-Na type is 0.2%, the ratio of R-Cl type is 6%, the fourth regeneration result is the ratio of R-Na type 0.15%, the ratio of R-Cl type Was 6%, and the same reproduction state as the reproduction result after 10 executions in Comparative Example 1 could be obtained by 4 reproductions.
Thus, in Example 1, compared with the conventional method of Comparative Example 1, a stable resin regeneration state can be obtained earlier, and the separation of the resin is improved by carbon dioxide injection, and reverse regeneration is prevented. I understand that
[0056]
Comparative Example 2
As a mixed bed type ion exchange desalting tower in the final stage of a two-bed / three-column mixed-pure water purifier, a cylindrical tower having a tower diameter of 250 mmφ and a height of 3.7 m was tested.
The tower is filled with 20 liters of newly regenerated cation exchange resin and 44 liter of freshly regenerated anion exchange resin, and after passing 11 m ^{3 of} tap water, both air backwashing and water backwashing are performed. The resin was separated. As a result of the first regeneration with cation exchange resin with hydrochloric acid and the anion exchange resin with sodium hydroxide, the ratio of the R-Na form to the entire cation exchange group after regeneration was 8.2%, and the anion exchange after regeneration was performed. The ratio of the R—Cl form to the total group was 43%.
[0057]
Similarly, after the tap water was passed through, the second resin regeneration was performed. As a result, the ratio of the R-Na form to the entire cation resin exchange group after the regeneration was 7.2%, and the whole anion resin exchange group after the regeneration. The ratio of the R-Cl form to 37% was 37%.
Further, after running tap water, the third regeneration was performed. As a result, the ratio of the R-Na form was 5% and the ratio of the R-Cl form was 31%.
[0058]
In the reproduction after 10 times of such repetition, the R-Na type ratio was 3.2% and the R-Cl type ratio was 28%, which was the same value as the ninth reproduction result.
As described above, in a normal mixed-bed tower, even if the separation and regeneration of the mixed resin is performed once, a large amount of the resin that cannot be regenerated remains, and the ratio of the resin that is not finally regenerated after 10 separation and regeneration may become constant. Recognize.
[0059]
Example 2
In the same apparatus as in Comparative Example 2, after replacing the regenerated new resin and replacing with the air backwashing in Comparative Example 2, a carbon dioxide containing gas containing 100% by volume of carbon dioxide was injected at 80 N liter / min for 5 minutes. The test was performed under the same conditions as in Comparative Example 2 except that the water was washed back and the separation operation was performed.
[0060]
That is, after passing 11 m ^{3 of} tap water, carbon dioxide was injected, and both resins were separated by backwashing with water. As a result of the first regeneration with cation exchange resin with hydrochloric acid and the anion exchange resin with sodium hydroxide, the ratio of the R-Na form to the entire cation exchange group after regeneration was 3.5%, and the anion exchange after regeneration was performed. The ratio of the R—Cl form to the total group was 29.5%.
Similarly, tap water was passed through and the resin was regenerated for the second time. As a result, the ratio of the R-Na form to the entire cation exchange group after regeneration was 3.2%, and the ratio of R-Na to the whole anion resin exchange group after regeneration was The proportion of Cl form was 29%.
[0061]
Further, after passing tap water, the third regeneration was performed. As a result, the ratio of the R-Na form was 3.2%, and the ratio of the R-Cl form was 28.4%.
[0062]
In the regeneration after 10 repetitions, the R-Na type ratio was 3.2% and the R-Cl type ratio was 27%, which was the same value as the third regeneration result.
As described above, in the first regeneration, the regeneration is performed up to a point close to the 10th regeneration in the conventional method of Comparative Example 2, and reaches a steady value in almost three regenerations, and the resin separability is improved by injecting carbon dioxide. It can be seen that reverse reproduction is prevented.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment in which the present invention is applied to a condensate demineralizer.
[Explanation of symbols]
1 demineralizer 1a, 1b, 1c strainer 2 ion exchange resin 3 cation regeneration tower 3a, 3b, 3c, 3d strainer 3e collector 4 anion regenerator 4a, 4b strainer 5 intermediate resin storage tank V ₁ ~V ₂₂ valve

Claims (3)

In the method of separating and regenerating the ion exchange resin forming the mixed bed,
Contacting the ion exchange resin in a mixed state with a carbon dioxide-containing gas containing 10% by volume or more of carbon dioxide ;
Separated into a cation exchange resin layer and an anion exchange resin layer by backwashing,
A method for separating and regenerating an ion exchange resin, wherein each resin layer is regenerated by contacting with a regenerant. The supply amount of the carbon dioxide-containing gas is 3 to 50 times the amount of the ion exchange resin in the mixed state, and the supply flow rate is 0.3 to 5 m. ³ -Gas / m ³ The method according to claim 1, characterized in that the resin / min. The method according to claim 1 or 2, wherein the separation and regeneration of the ion exchange resin forming the mixed bed is the first to tenth separation and regeneration after the introduction of a new resin or after the replenishment of the resin.

Images